The Trail du Four à Chaux is a forest trail race held in Nandy, located in Seine-et-Marne, east of Paris within the Île-de-France region. Taking place in early October, it offers participants two one-loop course options: an 11 km route with 170 m of elevation gain, or a 28 km route with 380 m of elevation gain. The longer 28 km course is the more frequently chosen option and can be completed individually or as a two-person relay.
The event emphasizes nature and woodland running, distinguishing itself from road races, and appeals to those seeking a trail running experience without venturing far from the Paris region. The previous edition saw over 200 participants for each distance, indicating a well-attended local race rather than an enormous event. Its motto, “Tu vas prendre chaud la bas,” translates to "you are going to heat up out there," aptly describing a challenging forest run with sufficient elevation to test participants on both distances.